Block coordination copolymers

ABSTRACT

The present invention provides compositions of crystalline coordination copolymers wherein multiple organic molecules are assembled to produce porous framework materials with layered or core-shell structures. These materials are synthesized by sequential growth techniques such as the seed growth technique. In addition, the invention provides a simple procedure for controlling functionality.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Provisional Application Ser. No.61/156,046 filed Feb. 27, 2009, the contents of which are herebyincorporated by reference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made under the support of the United StatesGovernment, United States Department of Energy though the NationalEnergy technology Laboratory under Award No. DE-FC26-07NT42121. TheUnited States Government has certain rights in the invention.

BACKGROUND OF THE INVENTION

Known substance classes of porous solids are called metal organicframeworks (MOF) or coordination polymers. The theory of coordinationbonds developed by Alfred Werner [A. Werner, Z. Anorg. Allg. Chem. 3(1893) 267] made it possible for the first time to understand theexperimental results of complex inorganic chemistry. Stable coordinationpolymers are obtained by adding organic molecules capable of complexformation, like diamines or diacids, to dissolved inorganic salts. Thedistances between the metal ions as coordination centers can be set in awide range through the structure, in particular of the organiccomponents, and result in micro- to mesoporous substances. Coordinationpolymers can thus be varied and are substantially documented [S.Kitagawa, et al. Angew. Chem. Int. Ed. 43 (2004) 2334].

The ability to synthesize coordination polymers with porosity results ina new class of materials that are crystalline molecular sieves. Theatomic structure of any coordination polymers can be determined by x-raycrystallography, the dimensions of the pores or channels can bedetermined with excellent certainty. The internal surface areas of someporous coordination polymers are significantly greater than other porousmaterials. The pore sizes/shapes are highly tunable and large pore sizescan be synthesized when compared to know zeolites. Functionalization ofthe backbones or frameworks in these materials can be achieved bystarting the synthesis with organic linkers with functional groupsalready installed or by post synthesis modification.

Recently, the coordination copolymerization method with twotopologically distinct linkers was reported, and can give rise to amicroporous coordination polymer (MCP) with a previously unattainablemesoporous structure [K. Koh, A. G. Wong-Foy and A. J. Matzger, Angew.Chem., Int. Ed., 47, (2008), 677]. The first example of this strategy,UMCM-1 (University of Michigan Crystalline Materials), illustrated thatinstead of a mixture of crystalline phases arising from the independentassembly of a single linker type, a novel phase incorporating allorganic components can be produced by controlling the mole ratio of eachorganic linker.

SUMMARY OF THE INVENTION

The present invention describes a new class of materials, coordinationcopolymers. Production of these materials involves sequential growthtechniques such as the seed growth method, and the three dimensionalpropagation of the second or higher shells generates the layer features.The materials may be used in processes such as separation processes andas catalysts for reactions.

The new material is a coordination copolymer comprising at least a firstcoordination polymer and a second coordination polymer wherein the firstand second coordination polymers are not identical. The firstcoordination polymer and the second coordination polymer may be presentin a first and second layered configuration. Optionally, at least athird coordination polymer may be layered on the second layer. The thirdcoordination polymer may be the same as the first layer. The thirdcoordination polymer may have a different composition or a differentstructure from that of either the first or the second coordinationpolymer. The first and second layered configuration may form a core andshell configuration. At least a third coordination polymer may belayered on the shell. The third coordination polymer may be the same asthe core. The third coordination polymer may have a differentcomposition or a different structure from that of either the first orthe second coordination polymer.

One method of making a coordination copolymer involves adding at leastone source of metal cations and at least one organic linking compound toa solvent to form a first solution or colloidal suspension; treating thefirst solution or colloidal suspension to form crystals of a firstcoordination polymer; adding at least one source of metal cations and atleast one organic linking compound to a solvent to form a secondsolution or colloidal suspension wherein the second solution is notidentical to the first solution or colloidal suspension; adding crystalsof the first coordination polymer to the second solution or colloidalsuspension; and treating the second solution or colloidal suspension toform crystals of a second coordination polymer as a layer over one ormore crystals of the first coordination polymer forming a coordinationcopolymer wherein the first coordination polymer is not identical to thesecond coordination polymer. The crystals of the first coordinationpolymer may be of a size ranging from about 10 nanometers to about 1micron. The coordination copolymers may be made by a “one-pot” method aswell. For example, a coordination copolymer may be made by adding atleast one source of metal cations and at least one organic linkingcompound in a solvent to form a solution or colloidal suspension;treating the solution or colloidal suspension to form crystals of afirst coordination polymer; adding at least one additional reagentselected from the group consisting of a second source of metal cations,a second organic linking compound, and a combination thereof, to thesolution or colloidal suspension; and treating the solution to formcrystals of a second coordination polymer as layer over one or morecrystals of the first coordination polymer forming a coordinationcopolymer wherein the first coordination polymer is not identical to thesecond coordination polymer.

The coordination copolymer may be used in a process for separating afirst component from a second component of a mixture by contacting themixture with a coordination copolymer comprising at least a firstcoordination polymer and a second coordination polymer wherein the firstand second coordination polymers are not identical. The coordinationcopolymer may also be used as a catalyst in a chemical reaction. Forexample, the coordination copolymer may be used for converting at leastone reactant by contacting a feed comprising at least one reactant witha coordination copolymer comprising at least a first coordinationpolymer and a second coordination polymer wherein the first and secondcoordination polymers are not identical and wherein at least onecoordination polymer comprises a catalytic function, to give a convertedproduct.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are microscope images of two-layer core-shellcoordination copolymers of the present invention.

FIGS. 2 a and 2 b are microscope images of multilayered coordinationcopolymers of the present invention

FIG. 3 is a plot of the amount of adsorbed nile red into (1) acoordination copolymer wherein the two coordination polymers of thecoordination copolymer are IRMOF-3 and MOF-5 and (2) a coordinationcopolymer wherein the two coordination polymers of the coordinationcopolymer is a cyclohexyl modified IRMOF-3 and MOF-5, as a function ofexposure time.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a novel class of materials called blockcoordination copolymers, which comprise at least two differentcoordination polymers. The two different coordination polymers arespatially contiguous and the coordination copolymer exhibits regions orblocks of the first coordination polymer and of the second coordinationpolymer. The at least two different coordination polymers may be porouscoordination polymers or non-porous coordination polymers or acombination thereof.

Processes described herein demonstrate the formation of blockcoordination copolymers which comprise at least two non-identicalcoordination polymers. For example, two coordination polymers may eachhave different pore sizes, and when used to form a single coordinationcopolymer the resulting multi-compositional coordination copolymer mayhave at least one portion having a first pore size and at least oneother portion having a second pore size. More than two coordinationpolymers may be used to form the multicompositional coordinationcopolymer resulting in multiple portions of the composite havingdiffering pore sizes. Thus, a novel class of materials with newproperties can be produced. One benefit of the process is that thecoordination polymers used to make the composite and hence the poresizes can be selected depending upon the application within which thecomposite will be used. Furthermore, depending upon the process ofmaking the composite, control may be exercised during the formation ofthe composite to locate a particular pore size in a specific region ofthe composite. Therefore, if desired, coordination copolymers may beformed for specific applications by selecting the starting coordinationpolymers and the process for making the coordination copolymer. It isenvisioned that a coordination copolymer may be synthesized to have ahigh selectivity as well as a high capacity in applications such as sizeselective separations and size and or shape selective catalysis.

Examples of suitable coordination polymers for use in synthesizing thecomposite coordination copolymer will be first described herein, andthen the process for forming the composite coordination copolymer willbe described.

The coordination polymers used to form a coordination copolymercomposite define a molecular framework. The coordination polymerscontain a plurality of metal atoms or metal clusters linked together bya plurality of organic linking ligands. The linking ligand coordinatestwo or more metal atoms or metal clusters. The organic linking ligandsmay be the same or different. The organic linking ligands may be chargeneutral, or each organic linking ligand is derived from a negativelycharged multidentate ligand. Characteristically the linking ligands of acoordination copolymer include a first linking ligand having a firstbackbone, and a second linking ligand having a second backbone. In themost common case, the first and second backbones are identical, having,for example, the same aromatic ring or straight chain hydrocarbonstructures. However, it is also understood that the first and secondbackbones may be different. For example, the first and second backbonesmay have different ring or straight chain structures; the first andsecond backbones may have the same ring or straight chain structures butbe substituted with different functional groups; or the first and secondbackbones may be hydrocarbons, or may have one or more atoms replaced bya heteroatom such as N, O, or S. The coordination copolymers may be incrystal form such as in crystal clusters, they may be catalyticallyactive, and the surface of the coordination polymer may be polar ornon-polar.

In one embodiment of the invention, each metal cluster of thecoordination copolymer includes one or more metal ions with the organiclinking ligands partially or fully compensating for the charges of themetal ions. In a specific embodiment, each metal cluster includes ametal ion or metalloid having a metal selected from the group consistingof Group 1 though 16 of the IUPAC Periodic Table of the Elementsincluding actinides, lanthanides, and combinations thereof. Specificexamples of useful metal ions include, but are not limited to, the metalion selected from the group consisting of Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺,Y³⁺, Ti^(4′), Zr⁴⁺, Hf⁴⁺, V⁴⁺, V³⁺, V²⁺, Nb³⁺, Ta³⁺, Cr³⁺, Mo⁺³, W³⁺,Mn³⁺, Mn²⁺, Re³⁺, Re²⁺, Fe³⁺, Fe²⁺, Ru³⁺, Ru²⁺, Os³⁺, Os²⁺, Co³⁺, Co²⁺,Rh⁺, Rh²⁺, Rh³⁺, Ir⁺, Ir³⁺, Ni², Ni⁺, Pd²⁺, Pd⁴⁺, Pt²⁺, Pt^(4′), Cu²⁺,Cu⁺, Ag⁺, Au⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Ga³⁺, In³⁺, TI³⁺, Si⁴⁺, Si²⁺,Ge⁴⁺, Ge²⁺, Sn⁴⁺, Sn²⁺, Pb⁴⁺, Pb²⁺, As⁵⁺, As³⁺, As⁺, Sb⁵⁺, Sb³⁺, Sb⁺,Bi⁵⁺, Bi³⁺and Bi⁺.

The coordination copolymers comprise coordination polymers that haveorganic linking ligands. In one embodiment of the invention, the organiclinking ligand may be described by Formula I:X_(n)Y   (I)wherein X is a functional group;

-   -   n is an integer that is equal to or greater than 2, and    -   Y is a hydrocarbon group or a hydrocarbon group having one or        morecarbon atoms replaced by a heteroatom.

In one embodiment, X is CE₂ ⁻, C(Ar)₂ ⁻, RC(=G)C═C(G′)R, orR¹C(ZR²)C═C(ZR²)R¹; E is O, S, Se, or Te; Z is N, P, or As; R R¹ R² areH, alkyl group, or aryl group; A is N, P, or As and G is O, S, Se, orTe. Suitable examples for X include, but are not limited to, CO₂ ⁻, CS₂⁻, ROPO₂ ⁻ 2, PO₃ ⁻², ROPO₃ ⁻², PO₄ ⁻², ROAsO₂ ⁻, AsO₃ ⁻², ROAsO₃ ⁻²,SO₃ ⁻, SO₄ ⁻, SeO₃ ⁻, SeO₄ ⁻, TeO₃ ⁻ or TeO₄ ⁻. In another embodiment, Ycomprises a moiety selected from the group consisting of monocyclicaromatic ring, a polycyclic aromatic ring, a monocyclic heteroaromaticring, a polycyclic heteroaromatic ring, alkyl groups having from 1 to 10carbon atoms, and combinations thereof. In another embodiment, Y isalkyl, alkyl amine, aryl amine, alkyl aryl amine, or phenyl. In yetanother embodiment, Y is a C₁₋₁₀ alkyl, a C₆₋₅₀ aromatic ring, or aC₄₋₂₄ heteroaromatic ring system. The organic linking ligands may be thesame throughout a coordination polymer, or more than one organic linkingligand may be incorporated in a coordination polymer.

In one embodiment of the invention, the coordination copolymers arecharacterized by having an average pore dimension from about 2 to about40 angstroms, from about 5 to about 30 angstroms, or from about 8 toabout 20 angstroms as determined by nitrogen adsorption. In anotherembodiment of the invention the coordination copolymers arecharacterized by having a surface area greater than about 2000 m²/g asdetermined by the Langmuir method. In another embodiment, thecoordination copolymers are characterized by having a surface area ofgreater than about 1000 to about 40000 m²/g as determined by theLangmuir method. In yet another embodiment, the coordination polymer hasa pore volume per grams of coordination polymer greater than about 0.1cm³/g as determined by nitrogen adsorption.

Furthermore, bulk properties of the multicompositional coordinationcopolymer may be controlled by varying the concentration of thedifferent linkers in solution during syntheses of at least one of thecoordination polymers, see Example 2. Controlling the bulk properties ofcoordination copolymers allow for the coordination copolymers to besynthesized for specific purposes which require specific bulkproperties. For example, controlling the surface area of thecoordination copolymer composite could allow an end user to use lessmaterial to accomplish a given task because of the higher surface areaprovides a significantly larger number of active sites.

Controlling the order of the addition of the linkers constitutes anapproach to making the coordination copolymer and can be considered aseeded growth technique involving epitaxial growth of metal organiccoordinated molecules with different components. The resultantcomposition of matter is a layered material derived from the nesting ofthe frameworks. Previously, techniques have relied on substitution ofmetal ions resulting in color contrast or magnetism changes. Thetechnique herein allows for engineering of multi layered crystallinestructure with different functionality. First, seeds of two differentcoordination polymers, A and B, are separately prepared such as by thesolvothermal process. Time and heat may be applied to allow seeds of thecoordination polymers A and B to grow. Typical crystallizationtemperatures range from ambient to 250° C., with reaction times fromminutes to months. Most common are crystallizations that take a fewhours to a few days at ambient to about 125° C. Examples of reactionstimes include from about 1 minute to about 5 months, or from about 2hours to about 4 days. Suitable solvents include formamides, sulfoxides,nitriles, esters, amines, ethers, ketones, aromatics, aliphatics, water,and combinations thereof. Specific examples of solvents include, but arenot limited to, ammonia, hexane, benzene, toluene, xylene,chlorobenzene, nitrobenzene, naphthalene, thipohene, pyridine, acetone,1,2-dichloroethane, methylenechloride, tetrahydrofuran, ethanolamine,triethylamine, N.N-dimethyl formamide, N,N-diethyl formamide, methanol,ethanol, propanol, alcohols, dimethylsulfoxide, choloroform, bromoform,dibromomethane, iodoform, diiodomethane, halogenated organic solvents,N,N-dimethylacetamide, N,N-diethylacetamide, 1-methyl-2-pyrrolidinone,amide solvents, methylpyridine, dimethylpyridine, and mixtures thereof.

Then, a portion of the respective reaction solutions are exchanged. Forexample, a portion of the reaction solution containing seeds ofcoordination polymer A is added to the reaction solution forcoordination polymer B; and a portion of the reaction solutioncontaining seeds of coordination polymer B is added to the reactionsolution for coordination polymer A. Of course, for purity, theseed-containing portions may be added to fresh reaction solutionsinstead of those used to generate the seeds. Time and heat may again beapplied causing a new layer of coordination polymer to grow on top ofthe primary layer already present, see Example 3. The procedure may bestopped at this point with a coordination copolymer having twocoordination polymers, one as a primary or core layer and the other as alayer over or surrounding the primary layer, such as a shell. Or, theprocedure may continue with one or more iterations causing additionallayers of coordination polymers to grow. The original two coordinationpolymers may be used to form alternating layers, or additional differentcoordination polymers may be used to create layers of differentcompositions. It is also within the scope of the invention to grow thefirst layer on a substrate with the second layer grown over the firstlayer and so on.

Through selecting different coordination polymers in the differentlayers, the coordination copolymer composition of matter may beengineered for a specific purpose. For example, a coordination polymerin the primary or core layer may contain large pore sizes, while acoordination polymer in the first layer over the primary layer maycontain smaller pore sizes. In this way, the material may be used as ahigh capacity selective adsorbent. The smaller pore coordination polymerlayer would operate to provide the selectivity, while the larger porecoordination polymer in the primary layer would operate to provide ahigh capacity. Tuning of the kinetics of guest uptake and release may bepossible. Other properties of the coordination copolymer may becontrolled in the same manner. Furthermore, multistage catalysts in asingle material may be formed.

By selecting at least one coordination polymer that has a catalyticfunction, the coordination copolymer may be used as a catalyst tocatalyze a reaction. For example, the coordination copolymer may be usedin a process for converting at least one reactant by contacting a feedcomprising at least one reactant with the coordination copolymercomprising at least a first coordination polymer and a secondcoordination polymer wherein the first and second coordination polymersare not identical and wherein at least one coordination polymercomprises a catalytic function, to give a converted product. In anotherexample, the reaction may be a hydrocarbon conversion reaction where afeed comprising hydrocarbons is contacted with a coordination copolymercomprising at least a first coordination polymer and a secondcoordination polymer wherein the first and second coordination polymersare not identical and wherein at least one coordination polymercomprises a catalytic function, to give a converted product. Hydrocarbonconversion process include reactions such as cracking, hydrocracking,aromatic alkylation, isoparaffin alkylation, isomerization,polymerization, reforming, dewaxing, hydrogenation, dehydrogenation,transalkylation, dealkylation, hydration, dehydration, hydrotreating,hydrodenitrogenation, hydrodesulfurization, methanation, ring opening,and syngas shift. In another embodiment, the catalytic functionality maybe added to the coordination copolymer after synthesis.

Examples 5-7 further demonstrate that a coordination polymer with aparticular crystal habit can be successfully layered on crystals of acoordination polymer with a different crystal habit. In general this isa difficult task to carry out successfully because crystals tend to growmost effectively on seeds of the same morphology and crystal habit. Forexample, prisms grow best on prisms and cubes grow best on cubes. On theother hand, crystals can also be heterogeneously nucleated onnanoparticles present in reaction mixtures supersaturated with respectto the reagents necessary to the nucleation and growth of a givencrystalline material. For example, ice crystals are heterogeneouslynucleated and then continue to grow as snowflakes on nano dust particlesin the atmosphere.

This process is enabled by preparing at least two types of crystals, butespecially the crystal of the first, or core layer, in a small, or nanocrystal size regime.

In one embodiment, the nanocrystals can range from 10 to 100 nm,although crystals approaching 500 nm and even one micron in size canstill be utilized as the core material. Often these nanocrystals aremore irregular in habit and morphology than larger crystals of the samematerial. However, despite their nano size and often less-wellpronounced crystal habit and morphology, the crystals can be easilyidentified by their characteristic powder XRD pattern. Likewise, when asecond layer is grown on the surface of the first layer, the secondmaterial's characteristic XRD pattern will appear in the final productXRD pattern as a separate set of peaks.

A key benefit of this process is that the crystals of the secondmaterial can be grown on crystals of the first or core layer in the samereaction solution used to grow the first material. Such in situ or“one-pot” syntheses are of significant practical importance because ofsuch issues as waste minimization and elimination of costly intermediateprocessing steps such as isolation and purification of the firstmaterial before subjecting the first material to the layering chemistryof the second layer. Nevertheless, in another embodiment of thisinvention, the crystals of the first layer are isolated and re-suspendin a supersaturated solution of the second material in order to grow thesecond material on the first material. This processing might be requiredwhere the solution chemistries or other processing conditions of the twomaterials are incompatible.

Another aspect of the “one-pot” Examples 5 through 7 is matching thechemistry of the material of the first or core layer with the chemistryof the second layer. This is important because, for example, the solventfor the first layer must be similar to, or the same as, the solvent forthe second layer. This is because the reagents for the preparation ofthe second layer must be added to a suspension of the nanocrystals ofthe first layer. If the reagents for the preparation of the secondmaterial are insoluble in the solvent from the preparation of the firstmaterial, or if these reagents react with another soluble reagent leftover in solution from the preparation of the first material, undesiredby-products and/or precipitates may form. On the other hand, thechemistry of the preparation of the second material may be tailored insuch a way as to react with, modify, and/or partially dissolve thecrystals of the first material. The resultant second layer on a firstmaterial composite might then possess a highly desirable physicalproperty such as enhanced porosity or crystal integrity.

In the examples, the selection of core and shell materials were based onthe offset placement of XRD peaks for the two respective materials. Thegeneral design of these experiments involves reducing reactants for eachproduct down to stoichiometric quantities, based on the molecularformula of the desired product. An equimolar amount of a base, such astriethylamine (TEA) was used per carboxylic acid function in order tofacilitate coordination of linker to metal or metal clusters. The firstor core material reaction is allowed to proceed for an appropriateperiod of time before the addition of pre-mixed reactants for the secondmaterial. Details are provided in Examples 5-7. Abbreviations as used inthe examples include:

-   H₃BTC—1,3,5-benzenetricarboxylic acid-   DMF—N,N-Dimethylformamide-   EtOH—Ethyl alcohol-   TEA—Triethylamine-   H₂BDC—1,4-benzenedicarboxylic acid-   Bipy—4,4′-bipyridyl    MOF formulas as used in the example include:-   HKUST-1 Cu₃BTC₂(H₂O)₃-   MOF-508 ZnBDC(bipy)_(1/2) DMF(H₂O)_(1/2)-   IRMOF-1 Zn₄O(BDC)₃-   MIL-53 Al(OH)(BDC)(H₂BDC)_(0.7)

As used in the examples below, an abbreviation of a coordinationcopolymer is as follows: a first MOF formula is recited, followed by thesymbol @, followed by a second MOF formula. Multiple copolymers in acoordination copolymer are shown by reciting multiple MOF formulas, eachseparated from the others by the symbol @. For example, IRMOF-3@MOF-5 isused to describe the coordination copolymer containing both IRMOF-3 andMOF-5; and MOF-5@IRMOF-3@MOF-508 is used to describe the coordinationcopolymer containing all three of MOF-5, MOF-3, and MOF-508. Note thatwhen the coordination copolymer has layers of MOFs, the order of thelayers may be reflected in the abbreviation.

The coordination copolymer derived from the ditopic linkerbenzene-1,4-dicarboxylate (BDC) and 2-amino benzene-1,4-dicarboxylate(ABDC) serves to illustrate the invention. As background, it is notedthat in the presence of zinc nitrate tetrahydrate and diethylforamide(DEF), pure benzene-1,4-dicarboxylic acid reacts to generate acoordination polymer, MOF-5, the crystal structure analysis of whichshows it to be a simple cubic net in the Fm-3m space group. Similarly,pure 2-amino benzene-1,4-dicarboxylic acid reacts to generate IRMOF-3which has isostructure with MOF-5. As the first examples, seeds of MOF-5and IRMOF-3 were separately prepared under the same solvothermal processas the synthesis of MOF-5. After 15 h, the respective reaction solutionswere exchanged, i.e. seed crystals of MOF-5 were immersed in theunreacted solution of ABDC and Zn(NO₃)₂, and vice versa. Heating thesolutions for another 15 h produced the coordination copolymers. Themicroscope image of the resultant products reveals core-shell cubes, seeFIG. 1 a and FIG. 1 b, with color contrast corresponding to white(MOF-5) and orange (IRMOF-3). FIG. 1 a shows IRMOF-3 as the shell layerand MOF-5 as the core layer, while FIG. 1 b shows MOF-5 as the shelllayer and IRMOF-3 as the core layer. The scale bar in FIGS. 1 a and 1 bis 200 μm. In both cases of MOF-5 and IRMOF-3 as seeds,core-shell-fashioned MOFs are successfully obtained. ¹H NMR analysisafter the decomposition with the core-shell MOFs showed that the molarcomposition of the block copolymer as BDC:ABDC=1:1, indicating thesuccessful formation of MOF shells growing from the anchor points ofcarboxylate groups on the surface of seeded MOFs. The N₂ uptake of bothcore-shell MOFs are 820 cm³/g for both IRMOF-3@MOF-5 and MOF-5@IRMOF-3,which are between that of MOF-5 (920 cm³/g) and that of IRMOF-3 (750cm³/g).

Applying the seed growth technique in presence of core-shell MOFs, themultilayered crystals can be also produced. Growth of new a layer fromthe core-shell seeds makes alternating of MOF-5 and IRMOF-3 layers. Twodifferent multilayered MOFs were successfully produced;MOF-5@IRMOF-3@MOF-5, as shown in FIG. 2 a, and IRMOF-3@MOF-5@IRMOF-3, asshown in FIG. 2 b. The scale bar in FIGS. 2 a and 2 b is 200 μm.

EXAMPLE 1 Preparation of Core-Shell MOFs

H₂ABDC (48 mg, 0.26 mmol) and H₂BDC (44 mg, 0.26 mmol) were charged to20 mL of vials, separately. Zn(NO₃)₂.4H₂O (0.208 g, 0.795 mmol) and 10mL of DEF were added to both vials. The mixtures were sonicated for 15min and heated at 100° C. After 15 h, cubic-shaped crystals were formedin both solutions. Then both solutions were decanted and switched witheach other. The mixtures were heated at 100° C. for another 15 h. Theproducts were washed with DEF and then soaked in CHCl₃.

EXAMPLE 2 Preparation of Multilayered MOFs

The preparation of core-shell MOFs as seeds was carried out in the sameway as described above in Example 1. After the formation of core-shellMOFs, the solution was decanted and the fresh mixture includingZn(NO₃)₂.4H₂O (0.208 g, 0.795 mmol) and H₂ABDC (48 mg, 0.26 mmol) orH₂BDC (44 mg, 0.26 mmol) in 10 mL of DEF was added. The mixtures wereheated at 100° C. for another 15 h. The products were washed with DEFand then soaked in CHCl₃.

EXAMPLE 3 Post-Modification of the Shell Part in the Core-Shell MOFs

Wet state of core-shell MOF (IRMOF-3@MOF-5, 10 mg) and 10 mg ofCyclohexyl isocyante were mixed in 1 mL of Chloroform. The mixture wasstirred by a shaking bath at room temperature for 3 days. Afterreaction, the products were washed with Chloroform.

EXAMPLE 4 Measurement of Diffusion of Nile Red into MOFs

MOFs were soaked in 5 ppm of nile red solution in chloroform. Inprescribed time, the absorbance of solutions was measured by a UV-visspectrometer. Using the calibration curve, the nile red concentration insolutions was calculated. From the decrease of the nile redconcentrations, the adsorbed amounts of the nile red into MOFs weremeasured. FIG. 3 is a plot of the amount of adsorbed nile red into (1) acoordination copolymer wherein the two coordination polymers of thecoordination copolymer are IRMOF-3 and MOF-5 and (2) a coordinationcopolymer wherein the two coordination polymers of the coordinationcopolymer is a cyclohexyl modified IRMOF-3 and MOF-5, as a function ofexposure time.

EXAMPLE 5 NanoMOF-508 on NanoHKUST-1

A suspension of nanoHKUST-1 was prepared by adding H₃BTC (0.5 g, 2.38mmol), DMF (8.3 mL), EtOH (8.3 mL), water (8.3 mL), and copper (II)nitrate (0.83 g, 3.57 mmol) to a glass jar with magnetic stirring atroom temperature. TEA (1 mL, 7.14 mmol) was slowly added, the jarsealed, and the cloudy blue suspension stirred at room temperature for3.5 hours. Meanwhile, a clear, colorless solution of H₂BDC (0.38 g, 2.37mmol), DMF (50 mL), EtOH (50 mL), bipy (0.19 g, 1.18 mmol), and zinc(II) nitrate (0.70 g, 2.37 mmol) was prepared in a glass beaker withmagnetic stirring at room temperature. This clear, colorless solutionwas slowly added to the nanoHKUST-1 suspension above, the jar sealed,and the mixture stirred. After 3 hours the suspension pH was 2-3. ATEA/DMF/EtOH (0.6, 41.7, 41.7 mL) solution was then slowly addeddropwise to the mixture, which was finally sealed and allowed to stirovernight. The turquoise solid was separated from the clear, colorlessliquid (pH˜5) by filtration through 0.45 μm filter paper, and then driedin a 60° C. oven under nitrogen overnight. Elemental analysis viainductively coupled plasma (ICP) on the filtrate solution revealed that<0.0001 mass % of Zn and Cu remained in solution after the reaction.Meanwhile, the XRD powder pattern for the solid material showed peaksfor both MOF-508 and HKUST-1, and ICP elemental analysis on the solidproduct revealed the presence of both metals, Cu and Zn.

EXAMPLE 6 NanoMOF-508 on NanoIRMOF-1

A suspension of nanoIRMOF-1 was prepared by adding H₂BDC (0.85 g, 5mmol), DMF (100 mL), and zinc (II) nitrate (3.0 g, 10 mmol) to a glassjar with magnetic stirring at room temperature. TEA (1.4 mL, 10 mmol)was slowly added, the jar sealed, and the cloudy white suspensionstirred at room temperature for 3.5 hours. Meanwhile, a suspension ofH₂BDC (0.38 g, 2.37 mmol), EtOH (50 mL), bipy (0.19 g, 1.18 mmol), andzinc (II) nitrate (0.70 g, 2.37 mmol) was prepared in a glass beakerwith magnetic stirring at room temperature. This milky suspension wasslowly added to the nanoIRMOF-1 suspension above, the jar sealed, andthe mixture stirred. After 3 hours the suspension pH was 3-3.5. ATEA/EtOH (0.7, 50 mL) solution was slowly added dropwise to the mixture,which was finally sealed and allowed to stir overnight. The white solidwas separated from the clear, colorless liquid (pH approximately 4) byfiltration through 0.45 μm filter paper, and then dried in a 60° C. ovenunder nitrogen overnight. Elemental analysis on the filtrate solutionrevealed about 0.16 mass % of Zn remained in solution after thereaction. Meanwhile, the XRD powder pattern for the solid materialshowed peaks for both MOF-508 and IRMOF-1, and elemental analysis on thesolid product revealed the presence of Zn.

EXAMPLE 7 NanoMlL-53 on NanoHKUST-1

A suspension of nanoHKUST-1 was prepared by adding H₃BTC (0.5 g, 2.38mmol), DMF (8.3 mL), EtOH (8.3 mL), H₂O (8.3 mL), and copper (II)nitrate (0.83 g, 3.57 mmol) to a glass jar with magnetic stirring atroom temperature. TEA (1 mL, 7.14 mmol) was slowly added, the jarsealed, and the cloudy blue suspension stirred at room temperature for3.5 hours. Meanwhile, a suspension of H₂BDC (0.58 g, 3.5 mmol), DMF (10mL), EtOH (10 mL), H₂O (10 mL) and aluminum (III) nitrate (2.6 g, 6.9mmol) was prepared in a glass beaker with magnetic stirring at roomtemperature. The cloudy white suspension was slowly added to thenanoHKUST-1 suspension above, the jar sealed, and the mixture stirred.After 3 hours the suspension pH was 1.5-2.5. A TENDMF/EtOH/H2O (0.96,7.7, 7.7, 8.7 mL) solution was slowly added drop-wise to the mixturewhich was finally sealed and stirred overnight. The blue suspension wascentrifuged at about 15,000 relative centrifugal force (rcf) for 1 hour,the mother liquor at pH 2-3 was decanted, and the solids were dried in a50° C. oven under nitrogen overnight. The XRD powder pattern for thesolid material showed peaks for both MIL-53 and HKUST-1, and elementalanalysis on the mother liquor revealed 0.094 mass % Cu and 0.11 mass %Al in solution.

1. A method of making a coordination copolymer comprising: a) adding atleast one source of metal cations and at least one organic linkingcompound to a solvent to form a first solution or colloidal suspension;b) treating the first solution or colloidal suspension to form crystalsof a first coordination polymer having a first x-ray diffractionpattern; c) adding at least one source of metal cations and at least oneorganic linking compound to a solvent to form a second solution orcolloidal suspension wherein the second solution is not identical to thefirst solution or colloidal suspension; d) adding crystals of the firstcoordination polymer to the second solution or colloidal suspension; ande) treating the second solution or colloidal suspension to form crystalsof a second coordination polymer having a second x-ray diffractionpattern as a layer over one or more crystals of the first coordinationpolymer forming a coordination copolymer comprising at least a firstregion of the first coordination polymer and at least a second region ofa second coordination polymer wherein the first coordination polymer isnot identical to the second coordination polymer and wherein the x-raydiffraction pattern of the coordination copolymer comprises both thefirst x-ray diffraction pattern and the second x-ray diffractionpattern.
 2. The method of claim 1 wherein the crystals of the firstcoordination polymer are of a size ranging from about 10 nanometers toabout 1 micron.
 3. The method of claim 1 wherein the treating of steps1b and le comprise temperatures ranging from ambient to about 250° C.and reaction times from about 1 minutes to about 5 months.
 4. The methodof claim 1 wherein the treating of steps 1 b and 1 e comprisetemperatures ranging from ambient to about 125° C. and reaction timesfrom about 2 hours to about 4 days.
 5. The method of claim 1 wherein thesolvent is selected from the group consisting of formamides, sulfoxides,nitriles, esters, amines, ethers, ketones, aromatics, aliphatics, water,and combinations thereof.
 6. The method of claim 1 further comprising:f) adding at least one source of metal cations and at least one organiclinking compound to a solvent to form a third solution or colloidalsuspension wherein the third solution or colloidal suspension is notidentical to the first or second solutions or colloidal suspensions; g)adding the coordination copolymer of 1 e) to the third solution orcolloidal suspension; and h) treating the third solution or colloidalsuspension to form crystals of a third coordination polymer as a layerover one or more crystals of the coordination copolymer forming a secondcoordination copolymer wherein the third coordination polymer has adifferent composition or structure than that of the second coordinationpolymer.
 7. The method of claim 1 further comprising: i) adding at leastone source of metal cations and at least one organic linking compound toa solvent to form a third solution or colloidal suspension wherein thethird solution or colloidal suspension is identical to the firstsolution or colloidal suspension; j) adding the coordination copolymerof 1 e) to the third solution or colloidal suspension; and k) treatingthe third solution or colloidal suspension to form crystals of a thirdcoordination polymer as a layer over one or more crystals of thecoordination copolymer forming a second coordination copolymer whereinthe third coordination polymer is the same as the first coordinationpolymer.
 8. The method of claim 1 further comprising, selecting at leastone organic linking compound in the first solution or colloidalsuspension and at least one organic linking compound in the secondsolution or colloidal suspension to control a characteristic of thecoordination copolymer.
 9. The method of claim 1 further comprising: l)adding the coordination copolymer of 1 e) to the first solution orcolloidal suspension; and m) treating the first solution or colloidalsuspension to form crystals of the first coordination polymer as a thirdlayer over one or more crystals of the coordination copolymer forming asecond coordination copolymer wherein the third layer has the samecomposition and structure as that of the first layer.
 10. A method ofmaking a coordination copolymer comprising: a) adding at least onesource of metal cations and at least one organic linking compound in asolvent to form a solution or colloidal suspension; b) treating thesolution or colloidal suspension to form crystals of a firstcoordination polymer having a first e-ray diffraction pattern; c) addingat least one additional reagent selected from the group consisting of asecond source of metal cations, a second organic linking compound, and acombination thereof, to the solution or colloidal suspension; and d)treating the solution to form crystals of a second coordination polymerhaving a second x-ray diffraction pattern as layer over one or morecrystals of the first coordination polymer forming a coordinationcopolymer comprising at least a first region of the first coordinationpolymer and at least a second region of a second coordination polymerwherein the first coordination polymer is not identical to the secondcoordination polymer and wherein the x-ray diffraction pattern of thecoordination copolymer comprises both the first x-ray diffractionpattern and the second x-ray diffraction pattern.
 11. The method ofclaim 10 wherein the crystals of the first coordination polymer are of asize ranging from about 10 nanometers to about 1 micron.
 12. The methodof claim 10 wherein the treating of steps 10b and 10d comprisetemperatures ranging from ambient to about 250° C. and reaction timesfrom about 1 minutes to about 5 months.
 13. The method of claim 10wherein the treating of steps 10b and 10d comprise temperatures rangingfrom ambient to about 125° C. and reaction times from about 2 hours toabout 4 days.
 14. The method of claim 10 wherein the solvent is selectedfrom the group consisting of formamides, sulfoxides, nitriles, esters,amines, ethers, ketones, aromatics, aliphatics, water, and combinationsthereof.
 15. The method of claim 10 further comprising: e) adding atleast one additional reagent selected from the group consisting of athird source of metal cations, a third organic linking compound, and acombination thereof, to the solution or colloidal suspension; f)treating the solution or colloidal suspension to form crystals of athird coordination polymer as a layer over one or more crystals of thefirst coordination copolymer forming a second coordination copolymerwherein the third coordination polymer layer is not identical to thesecond coordination polymer.
 16. The method of claim 15 wherein thethird coordination polymer has the same composition and structure as thefirst coordination polymer.
 17. The method of claim 15 furthercomprising: g) adding at least one additional reagent selected from thegroup consisting of an Nth source of metal cations, an Nth organiclinking compound, and a combination thereof, to the solution orcolloidal suspension, where N is an integer greater than 3; h) treatingthe solution or colloidal suspension to form crystals of a Nthcoordination polymer as a layer over one or more crystals of the (N-1)coordination copolymer forming a coordination copolymer wherein the Nthcoordination polymer layer is not identical to the (N-1) coordinationpolymer.
 18. The method of claim 10 further comprising: i) adding thecoordination copolymer of 10d) to a second solution or colloidalsuspension of at least one source of metal cations and at least oneorganic linking compound solvent; and j) treating the second solution orcolloidal suspension to form crystals of a third coordination polymer asa layer over one or more crystals of the coordination copolymer forminga second coordination copolymer wherein the third coordination polymeris not identical to the second coordination polymer.
 19. The method ofclaim 18 wherein the third coordination polymer has the same compositionand structure as the first coordination polymer.